#include <stdio.h>

int main(){
    int sign=1;
    double deno=2.0,sum=1.0,term;
    while (deno<=100)
    {
        sign=-sign;
        term=sign/deno;
        sum=sum+term;
        deno=deno+1;
    }
    printf("%f\n",sum);
    return 0;
}